CN1883859A - Method of working nitride semiconductor crystal - Google Patents
Method of working nitride semiconductor crystal Download PDFInfo
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- CN1883859A CN1883859A CN 200610093295 CN200610093295A CN1883859A CN 1883859 A CN1883859 A CN 1883859A CN 200610093295 CN200610093295 CN 200610093295 CN 200610093295 A CN200610093295 A CN 200610093295A CN 1883859 A CN1883859 A CN 1883859A
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Abstract
In a method of working a crystal, when a nitride semiconductor crystal (1) is worked, voltage is applied between the nitride semiconductor crystal (1) and a tool electrode (3) to cause electrical discharge, so that the crystal is partially removed and worked by local heat generated by the electrical discharge.
Description
Technical field
The present invention relates to the method for processing semiconductor crystal, more specifically, relate to the method for working nitride semiconductor crystal.
Background technology
Usually, cutting tool such as inner diameter blade or scroll saw are used for downcutting substrate from the semiconductor billet of silicon etc.The compound semiconductor crystal ingot of GaAs, InP etc. also is to cut with multi-thread sawing, as described in Japanese patent application publication No. 09-017755 for example.
Among compound semiconductor, nitride semiconductor crystals such as GaN have wide band gap, therefore as being suitable for sending the LED (light emitting diode) of short wavelength light or the semiconductor of LD (laser diode), its demand are increased day by day.Therefore, be desirably under the lower cost, with the growth crystal ingot of simple and efficient mode working nitride semiconductor.
Yet, because the nitride semiconductor crystals such as GaN among the compound semiconductor have high rigidity and low toughness, be difficult to by cutting such element nitride crystal with those identical apparatus and method that are used for Si crystal or GaAs crystal, often going wrong produces and ripple as the crack on the surface (hereinafter referred to as the cutting surface) that forms by cutting.Especially, because the GaN crystal has low toughness, be easy to cause crack or fracture.In addition,, distribute, because the distortion that cutting causes is easy to take place according to the hardness in the crystal because the GaN crystal has high rigidity and is made up of two kinds of elements.Therefore, for superior returns ground cutting GaN crystal ingot, need to reduce the broaching load amount, this can cause the reduction of output.
In addition, in the growth course of semiconductor billet, polycrystalline part (part with low crystalline quality) is in the growth of the neighboring area of semiconductor billet.Although this neighboring area should be removed, the periphery that grinds the nitride-based semiconductor crystal ingot is easy to cause the crack.When crystal ingot is longer, also be difficult to add section chief's crystal ingot with core drill, cause the heavy wear of instrument.In addition, because this processing needs abrasive particle and emery wheel, its cost of having relatively high expectations.Especially, residual stress is in the polycrystalline segment set of the neighboring area of GaN crystal ingot, if therefore stress equilibrium forfeiture during processing spontaneously produces the crack owing to the low-intensity of crystal.In addition, when core drill was used for adding section chief's crystal ingot, working fluid was difficult to permeate the position by processed, made thus to be difficult to provide gratifying processing.
Summary of the invention
In view of the situation of above-mentioned prior art, an object of the present invention is to provide a kind of can be under low cost, with the simple and technology effective and efficient manner working nitride semiconductor crystal.
In method according to working nitride semiconductor crystal of the present invention, when working nitride semiconductor crystal, voltage is applied to guiding discharge between described crystal and the tool-electrode, so that described crystal block section is removed and processing by the localized heat of described discharge generation.
Can use wire electrode to cut nitride semiconductor crystal as tool-electrode.Preferably, wire electrode is made by tungsten or molybdenum.By this way, the crystal ingot by the cutting nitride semiconductor crystal can obtain the nitride semiconductor crystal substrate.In addition, behind the cutting nitride semiconductor crystal, by surperficial with the inswept once more described cutting of described wire electrode, can be with the cutting surface smoothingization of crystal.On the other hand, further the nitride semiconductor crystal substrate that cutting obtains is passed through in etching.In addition, can further polish the nitride semiconductor crystal substrate that obtains by cutting.
In addition, when the neighboring area of nitride-based semiconductor crystal ingot comprises when comparing the part with low crystalline quality with the crystal ingot interior zone, can comprise the crystal ingot of described low crystalline quality part with the direction cutting vertical with the crystal ingot direction of growth.In addition, can remove the inhomogeneities on the growing surface of nitride-based semiconductor crystal ingot, to obtain to have the crystal ingot of inhomogeneities less than the surface of 30 μ m.
Use can be cut the nitride-based semiconductor crystal ingot according to cutting method of the present invention, so that its peripheral part with low crystalline quality is partly separated with the good crystalline of described crystal ingot inside.More clearly, in described nitride-based semiconductor crystal ingot, form through hole, then described wire electrode is passed through described through hole,, do not process peripheral part with low crystalline quality so that take out the good crystalline part of described crystal ingot inside so that described through hole becomes the cutting starting point.Use is according to processing method of the present invention, also can be by the longitudinal direction of described wire electrode is removed the edge of the end on described nitride semiconductor crystal surface from the angle perpendicular to 0-60 ° of the direction inclination on the described surface of described nitride semiconductor crystal.
In addition, by the morphology of described tool-electrode being transferred to the required morphology that can form on the described crystal on the described nitride semiconductor crystal.In addition, by use surface roughness Ry less than 10 μ m and glacing flatness less than the described tool-electrode of 20 μ m, remove the inhomogeneities on the described plane of crystal, to obtain surface roughness Ry less than 10 μ m and glacing flatness smooth surface less than 20 μ m.
By following detailed description with the accompanying drawing of the present invention, it is more apparent that above and other objects of the present invention, feature, aspect and advantage will become.
Description of drawings
Fig. 1 is schematic perspective view, illustrates the method for downcutting substrate from the nitride-based semiconductor crystal ingot by wire discharge processing in one embodiment of the invention.
Fig. 2 is schematic structure chart, illustrates an example of the general structure of wire electrical discharge machine.
Fig. 3 is schematic structure chart, illustrates the example of the general structure of electrical discharge machine in applying charge is processed with the situation that forms curved surface.
The specific embodiment
As mentioned above, in the typical method of production Semiconductor substrate, the growth crystal ingot is then by grinding or using core drill to remove the peripheral part that it has low crystalline quality.Afterwards, the cutting crystal ingot is to obtain to have the section of desired thickness.The cutting surface finish and being etched with of section is flattened, remove processing influence layer thus, clean section then to remove the lip-deep impurity of cutting.
For Si, GaAs etc., use inner diameter blade or scroll saw to cut its crystal ingot.Yet because its high rigidity and low toughness, nitride semiconductor crystal is easy to cause the crack, and because it contains two kinds of elemental compositions, because hardness distributes, is difficult to carry out linear incision on its crystal ingot.Although under the cutting load low speed that reduces, cut, yet it causes the reduction of output so that suppressing the crack generation is effectively.In addition, although for linear incision, increase instrument thickness so that keeping instrument intensity also is effectively, the cutting surplus that it requires crystal ingot to increase has reduced the material earning rate that obtains thus.Therefore, use conventional machine cuts technology, be difficult to obtain simultaneously gratifying cut quality and output for nitride semiconductor crystal.
Under these situations, found first and can process gratifying cut quality, higher output and the lower cost that obtains simultaneously nitride semiconductor crystal by discharge as inventor's result of study.Clearly, need abrasive material with the scroll saw cutting, because it is a machining, so it needs the cost of auxiliary material.By contrast, discharge cutting does not need abrasive material, because by apply the shelf depreciation that voltage produces in the water of the resistance with adjusting or oil, with the workpiece local melting.
Fig. 1 is schematic perspective view, illustrates the method for downcutting substrate from the nitride-based semiconductor crystal ingot by wire discharge processing.As shown in the figure, be fixed to nitride-based semiconductor crystal ingot 1 on the support 2 and be immersed in and cool off in dielectric such as deionized water or the kerosene.Then, wire electrode 3 is applied to voltage between wire electrode 3 and the crystal ingot 1 near crystal ingot 1.As a result, between wire electrode 3 and crystal ingot 1, produce local and small discharge, cut then along with being undertaken by the local crystal ingot material of removing of the heat of discharge generation.
Because the material of wire electrode 3 also is consumed in the discharge process, wire is in discharge position attenuation.Therefore, wire electrode 3 is moving so that prevent local attenuation and fracture in the discharge process with constant speed on its longitudinal direction.In addition, wire 3 and crystal ingot 1 relatively move by SERVO CONTROL, so that wire 3 carries out along with cutting and cuts in the crystal ingot 1.
Fig. 2 is schematic structure chart, illustrates an example of the general structure of this electrical discharge machine of wire.This figure understands that for example wherein big workpiece carries out the situation of wire discharge processing.Workpiece 1a is fixed on can be respectively on the cross table 11a and 11b that drive on X-direction of principal axis and the Y-direction of principal axis.12a is connected in upper table 11a with X-axle motor, and Y-axle motor 12b is connected in lower table 11b.By NC (digital control) device 13 control X-axle motor 12a and the Y-axle motor 12b that comprise servo circuit.
In workpiece 1a, form through hole in advance, wire electrode 14 is passed through through hole.Particularly, metal wire 14 is provided by feed rolls 15a, and running is by top roll 16a and upper guide 17a, then by workpiece 1a.Afterwards, wire 14 running is by guider 17b and lower roll 16b down, then with it on takers-in 15b.
During discharge processing, working fluid 18a such as the deionized water that is contained in the working fluid groove 18 is supplied to processing component by pump 19.Incidentally, have under the situation that can be submerged in the size in the working fluid groove, whole work-piece can be immersed in the working fluid groove of device with purifying working fluid at workpiece.By working fluid is supplied to processing component, the voltage of the power supply of self discharge in the future 20 is applied between workpiece 1a and the wire 14.The voltage of the power supply of self discharge in the future 20 imposes on wire 14 by power feeder 17e.
Therefore, between workpiece 1a and wire 14, produce local and small discharge, and the cutting of workpiece 1a is carried out.In this case, by cross table 11a and 11b, can on directions X and Y direction, move freely workpiece 1a respectively, form crooked arbitrarily line of cut 1b thus.In order to keep stable discharge processing, discharge information between wire 14 and the workpiece 1a is fed back to NC device 13 from discharge power supply 20, based on described information, NC device 13 fine adjustments apply voltage and cross table 11a and the 11b relative moving speed with respect to wire 14 then.
Incidentally, though a kind of wire electrode can be used in typical discharge metal silk cutting mechanics as shown in fig. 1, carrying out a kind of cutting processing, but, also can carry out multiple cutting processing simultaneously by providing the mechanism that electrifies to be used for downcutting Semiconductor substrate from crystal ingot to known multifibres saw.
Although have the cutting speed that larger-diameter wire electrode provides improvement and can carry out linear incision, its requires the cutting surplus that increases.On the other hand, wire electrode should be made by the material with satisfactory electrical conductivity and thermal conductivity, and this material can be preferably selected from brass, TC etc.Have high-intensity wire electrode for needs, can preferably use brass plating iron wire, tungsten filament, molybdenum filament etc.In other words, preferred use at high temperature has the wire of high tensile, so that prevent the wire electrode fracture.
In addition, owing to electrode (wire) also partial melting in the discharge process, one or more elements that constitute electrode adhere to the surface that is processed to form by this.This adhesion can be suppressed by refractory metal such as tungsten or molybdenum are used for electrode.
The example of nitride semiconductor crystal comprises AlN, GaN, InN and their mixed crystal.These nitride semiconductor crystals can pass through growths such as sublimation method, HVPE (halide vapor phase epitaxy), melting method.
After the nitride-based semiconductor crystal ingot downcuts substrate, its quality of cut surface can be by with wire cutting surface of inswept substrate once more under underload, and improves at aspects such as glacing flatness, surface roughness, processing influence layers.Improve by these, can reduce polishing and the required surplus of etching in subsequent handling, even can omit polishing process.Certainly in subsequent handling, carry out etching and polishing so that improve the surface roughness on cutting surface and remove processing influence layer.Can repeat repeatedly, until obtaining required surface quality with the inswept cutting of wire surface.
When nitride semiconductor crystal was grown, the crystal growth with well-crystallized quality saw in the zone in the central, and can have the part of low crystalline quality in its neighboring area.Because residual stress concentrations is in the part of low crystalline quality, after removal had the neighboring area of low crystalline quality, routine was carried out cutting work.On the contrary, the mechanical load that is applied on the crystal in discharge processing is so little, so that cutting work can be carried out under the part that will hang down crystalline quality is stayed the situation of neighboring area.Although the crystal that obtains by cutting under the situation of not removing the part with low crystalline quality can carry out surface finish and etching, it also can carry out surface finish and etching after suitably removing low crystalline quality.
In addition, when nitride semiconductor crystal was grown, its growing surface caused the inhomogeneities of the about 1mm of level difference sometimes.Can obtain the crystal of surface level difference by the inhomogeneities that discharge processing is removed on the growing surface less than 30 μ m.
The crystalline material that cuts that discharges is not limited to nitride semiconductor crystal, and any conductive crystal material can cut by the mode of discharge cutting.Method of the present invention also can be used for material such as the diamond or the SiC of high-speed cutting high rigidity, suppresses the generation of cutting loss and processing influence layer.
Usually, for the crystal ingot of Si crystal or GaAs crystal, remove its periphery by grinding usually.In this case, having in the crystal such as nitride-based semiconductor crystal ingot of residual stress its peripheral concentrating, rupturing when periphery is ground is easy to take place.In order to address this problem, can interior section to be dug out by core drill, thereby during processing, keep the stress equilibrium of edge stress concentrated part.Yet when crystal ingot had length above 10mm, it became and is difficult to provide working fluid to part to be processed, makes to be difficult to process on material.As a result, produce the problem that expends such as rupture generation and instrument.
On the other hand, in discharge processing, can easily provide working fluid (cooling fluid), because can exist wire electrode to penetrate the hole of crystal to be cut by it.In addition, owing to can use the discharge processing and do not need abrasive particle and emery wheel of cheap wire electrode and power supply, can be simply and worked crystal at an easy rate.
In addition, wire electrode can be applied to from the periphery of the substrate of crystal ingot cutting-out, the angle that it is tilted to be scheduled to by the first type surface with respect to substrate is with the edge of removal or rounding periphery.
Fig. 3 is schematic structure chart, illustrates another example of the general structure of electrical discharge machine.Although the electrical discharge machine of Fig. 3 is similar to Fig. 2, Fig. 3 understands that for example discharge is processed to form the situation of morphology.
In Fig. 3, the working fluid groove 18 that contains working fluid 18a is shelved on XY platform (stage) 12c.Workpiece 1c is immersed among the working fluid 18a.NC device 13a control XY platform 12c and Z-axial brake device 17c.The working electrode 14a (being called geometry (geographic) working electrode afterwards) that is used to form morphology is connected to the lower end of Z-axial brake device 17c.
Working fluid 18a in the groove 18 is by 21 circulations of working fluid purification devices.Especially, be stored among the first groove 21a of working fluid purification devices 21, transfer among the second groove 21c by filter 21b then from the working fluid 18a of groove 18.Afterwards, the working fluid 18a of purifying turns back to the working fluid groove 18 from the second groove 21c.
In the future the voltage of self discharge power supply 20a is applied between the workpiece 1c and geometry working electrode 14a in the working fluid groove 18.Then, produce local and small discharge between workpiece 1c and geometry working electrode 14a, the processing of the geometry on the workpiece 1c is carried out then.In this case, be fed back to NC device 13a about the information 13b of the discharge between workpiece 1c and geometry working electrode 14a, based on this information can meticulous adjusting workpiece 1c and geometry working electrode 14a between distance and apply voltage.
In this geometry discharge processing, processing can be carried out along any curved surface.Much less use straight plane electrode also can carry out plane processing.
First embodiment
In the first embodiment of the present invention, the cutting of on the gallium nitride of diameter 50mm that grows by HVPE and thickness 30mm, discharging.This crystal contains aerobic as alloy, and it has 4 * 10
18Cm
-3Carrier concentration and 1 * 10
-2The resistance of Ω cm.As shown in Figure 1, crystal 1 is fixed on the metallic support 2, metallic support 2 is clipped on the electric discharge device with electroconductive binder.Use the wire electrode 3 (TWS-100 by Sumiden FineConductors made) of diameter as the tungsten of 0.1mm.Cut on impregnated in the crystal of insulation in the water, described water is conditioned and has the resistance of 70000 Ω.With the speed supply of wire with 12m/min, operating current is set to 7 value, and operating voltage is set at 60V.Under the voltage feedback, under the constant discharge condition, finish cutting cost 5 hours.
The substrate thickness that downcuts is 500 μ m, is 140 μ m as the cutting loss of notch width.In addition, the warpage of the substrate of cutting-out is 12 μ m.In addition, the cutting surface of substrate has the surface roughness Ra of 420nm and the surface roughness Ry of 4700nm.
Particularly, surface roughness Ra is the value by following acquisition: the 10 μ m that sample along its average surface from the coarse curved surface of measuring * 10 μ m square is as the reference zone, the absolute value of the bias of curved surface in average surface and the sampling area is asked summation, and ask the mean value of summation with reference zone.Surface roughness Ry is the value by following acquisition: the 10 μ m that sample along its average surface from coarse curved surface * 10 μ m square is asked summation to the height and the average surface at top to the degree of depth of lowest trough with average surface in the sampling area as with reference to the zone.Incidentally, glacing flatness is meant in the whole zone to be measured in sample the summation of the degree of depth of the height of peak on perpendicular to the direction of reference surface and minimum point.
Second embodiment
In the second embodiment of the present invention, to use to be similar among first embodiment those condition and to cut, it is that the molybdenum filament (TM-100 is made by Sumiden FineConductors) of 0.1mm is as wire electrode that difference is diameter.Also spend 5 hours in a second embodiment and finish cutting.
The substrate thickness that downcuts is 500 μ m, is 150 μ m as the cutting loss of notch width.In addition, the warpage of the substrate of cutting-out is 15 μ m.In addition, the cutting surface of substrate has the surface roughness Ra of 480nm and the surface roughness Ry of 5200nm.
The 3rd embodiment
The third embodiment of the present invention and the first embodiment difference only are: the brass wire (SS-15HN, by Sumiden Fine Conductors preparation) that with diameter is 0.15mm is to be set at 11 value and operating voltage at operating current to be set under the 60V and to carry out as wire electrode and cutting.In the 3rd embodiment, spend two hours and finish cutting, make it possible to cut at short notice.On the other hand, have the diameter bigger than first embodiment owing to be used for the wire electrode of the 3rd embodiment, the cutting loss is increased to 190 μ m.
First comparative example
As first comparative example, use the multifibres saw device, on the gallium nitride identical, cut with first embodiment.0.16mm the piano wire of diameter is used as the silk saw, and diamond particles is used as abrasive particle.In first comparative example, cost reaches 60 hours finishes cutting, and the cutting loss is 200 μ m.If cut under the condition of finishing cutting after the possibility of consideration with the high-speed cutting of silk saw in 10 hours, when the silk saw passed through the attached neighbour in crystal ingot center, its Cutting Length and mechanical load increased, and produce the crack in the substrate that causes downcutting.Therefore, can not carry out gratifying cutting.
The 4th embodiment
In the fourth embodiment of the present invention, carry out Wet-type etching on the GaN substrate that in the 3rd embodiment, downcuts.The substrate dipping is in the etching solution of 50 ℃ of heating that described etching solution is the KOH solution of 2 normal concentrations, so that remove the thickness of GaN crystal N side surface 5 μ m.Because GaN crystal Ga side surface has high chemical resistance, it is proved aspect thickness not by enough etchings.Although the substrate before the etching is because the processing influence layer that wherein forms by discharge processing has the warpage of 20 μ m, the warpage of removing back substrate by etching at processing influence layer is improved to 10 μ m.
In addition, etched substrate is put on the polishing support, polished by dead load type grinder then.The diamond slurry of particle that will contain diameter and be 6 μ m and 2 μ m is used separately as surface plate as polishing agent with copper surface plate and tin surfaces plate.Obtain minute surface in this polishing back.The surface roughness Ra of Ga side surface and surface roughness Ry are respectively from polishing 4.5nm and the 50nm after preceding 480nm and 5300nm are reduced to polishing.Therefore, smoothedization of surface roughness after the polishing is to 1% of the preceding surface roughness of polishing.
The 5th embodiment
In the fifth embodiment of the present invention, with those identical conditions of first embodiment under on gallium nitride, cut, then under underload with the wire electrode cutting surface of inswept substrate once more, so that remove the lip-deep plane of crystal of cutting thinly.In this case, approach wiry is set at 5 μ m, and operating current is set at 4 value, and operating voltage is set at 50V.Use this wire inswept, smoothedization of surface roughness on the cutting surface of substrate is to the surface roughness Ra of 120nm and the surface roughness Ry of 1400nm.
The 6th embodiment
In the sixth embodiment of the present invention, on the GaAs of 50mm diameter substrate, by HVPE, the gallium nitride of growth 54mm diameter and 30mm thickness.Because also in the transversely growth of extending from substrate GaAs substrate, the crystal of growth comprises that the width of its neighboring area is about the low crystalline quality part of 2mm to gallium nitride.
(Cu: W=30: 70), the processing of discharging in kerosene is to form the through hole of contiguous gallium nitride periphery for the needle-like copper-tungsten electrode of use 1mm diameter.With the brass wire of 0.2mm diameter by through hole with the processing of discharging.Remove the peripheral part of nitride semiconductor crystal, cut nitride semiconductor crystal then, to obtain the plate-like crystal with well-crystallized quality of 50mm diameter.
Second comparative example
In second comparative example, with the 6th embodiment in carry out periphery on the identical gallium nitride (diameter 54mm and thickness 30mm) and grind.More specifically, use the bonding skive of vitrifying, and grind at emery wheel and carry out under with rotating conditions under the 500rpm.In this second comparative example,,, cause producing in the nitride semiconductor crystal crack owing to big internal stress in the crystal though the peripheral part of low crystalline quality is ground and removes.Therefore, can not obtain the plate-like crystal from part with well-crystallized quality.
The 7th embodiment
In the seventh embodiment of the present invention, in the 6th embodiment, stand the processing of discharging on the crystal of the 50mm diameter that periphery grinds, so that remove the lip-deep inhomogeneities of cutting, and so will cut surface smoothingization.Using surface roughness Ry is 1 μ m, and glacing flatness is that 5 μ m and diameter are the copper-tungsten electrode with straight circular working surface of 60mm, the processing of discharging in kerosene.Although the cutting surface of substrate has the inhomogeneities of 500 μ m in the discharge first being processed, obtaining surface roughness Ry by this processing is that 8.5 μ m and glacing flatness are the smooth surface of 15 μ m.
The 8th embodiment
In the eighth embodiment of the present invention, the cutting of on the Si-doped gallium nitride crystal that synthesizes by HVPE, discharging.At first, the gallium nitride of growth 58mm diameter and 5mm thickness on the GaAs of 54mm diameter substrate.In this case, the cross growth by crystal is forming the part of hanging down crystalline quality in the thickness range of the about 2mm of crystal ingot periphery.In addition, the growing surface of crystal ingot has the inhomogeneities that level difference is about 1mm.
Use the brass wire of 0.2mm diameter, the processing of in purified water, on the nitride-based semiconductor crystal ingot, discharging.In this case, cutting is carried out on perpendicular to the direction of the crystal ingot direction of growth.
As a result, from comprising the low crystalline quality crystal ingot partly of its neighboring area, can downcut the substrate of the low crystalline quality 0.5mm thickness partly that comprises the neighboring area.In this case, spend two hours and finish cutting, the cutting loss has the width of 0.28mm, and it does not have problems.By repeating identical cutting operation, can downcut 5 substrates.The cutting surface of the substrate that obtains has the inhomogeneities less than the level difference of 30 μ m.Therefore, by the growing surface of the crystal ingot of cutting into slices thinly, crystal ingot can be formed as its lip-deep inhomogeneities and be set to crystal ingot less than the level difference of 30 μ m.
The 3rd comparative example
In the 3rd comparative example, on as the crystal ingot that comprises the low crystalline quality part in its neighboring area among the 8th embodiment, cut by using the silk saw.In this case, use the bonding material wire that comprises bonding diamond abrasive grain, wire has the diameter of 0.25mm.Spend 45 hours and finish cutting, the cutting loss has the width of 0.3mm.If cutting is to finish under the condition of cutting to carry out, in the low crystalline quality part process in cutting neighboring area, in the neighboring area, produce the crack in 15 hours.Therefore, can not carry out gratifying cutting.
As mentioned above, the present invention can be provided in low-cost down, with the simple and technology effective and efficient manner working nitride semiconductor crystal.Can improve the production efficiency of the various semiconductor devices that use the nitride semiconductor crystal manufacturing thus, and therefore reduce production costs.
Although described in detail and for example clear the present invention, know to be understood that the present invention illustrates with the mode of embodiment to describe by way of example, not to limit by any way, the spirit and scope of the present invention only are subjected to the restriction of the clause of appended claim.
Claims (14)
1. the method for a working nitride semiconductor crystal, wherein, when working nitride semiconductor crystal (1), voltage is applied to guiding discharge between described crystal and the tool-electrode (3), so that described crystal block section is removed and processing by the localized heat of described discharge generation.
2. according to the method for the working nitride semiconductor crystal of claim 1, wherein use wire electrode to cut described crystal as described tool-electrode.
3. according to the method for the working nitride semiconductor crystal of claim 2, wherein said wire electrode is made by tungsten or molybdenum.
4. according to the method for the working nitride semiconductor crystal of claim 2, wherein obtain the nitride semiconductor crystal substrate by the crystal ingot that cuts described nitride semiconductor crystal.
5. according to the method for the working nitride semiconductor crystal of claim 2, after the described cutting of wherein said crystal, the surface that forms by described cutting is by the smoothing with the inswept once more described surface of described wire electrode.
6. according to the method for the working nitride semiconductor crystal of claim 2, the described crystalline substrates that obtains by described cutting of etching wherein.
7. according to the method for the working nitride semiconductor crystal of claim 2, wherein polishing is by the described crystalline substrates of described cutting acquisition.
8. according to the method for the working nitride semiconductor crystal of claim 2, the neighboring area of the crystal ingot of wherein said nitride semiconductor crystal comprises compares the part with low crystalline quality with its inside, and comprises the crystal ingot of described low crystalline quality part with the direction cutting vertical with the crystal ingot direction of growth.
9. according to the method for the working nitride semiconductor crystal of claim 2, wherein will remove to obtain have the crystal ingot of inhomogeneities in the inhomogeneities on the crystal ingot growing surface of described nitride semiconductor crystal less than the surface of 30 μ m.
10. according to the method for the working nitride semiconductor crystal of claim 2, wherein cut the crystal ingot of described nitride semiconductor crystal, so that its peripheral part with low crystalline quality is partly separated with the good crystalline of described crystal ingot inside.
11. method according to the working nitride semiconductor crystal of claim 10, wherein in described crystal ingot, form through hole, then described wire electrode is passed through described through hole, so that described through hole becomes the cutting starting point, do not process peripheral part with low crystalline quality so that take out the good crystalline part of described crystal ingot inside.
12. method according to the working nitride semiconductor crystal of claim 2, wherein, after downcutting substrate, by the longitudinal direction of described wire electrode is removed the edge of described substrate surface end from tilt 0-60 ° angle of the direction perpendicular to the described surface of described substrate from the crystal ingot of described nitride semiconductor crystal.
13., wherein on described crystal, form required morphology on the described crystal by the morphology of described tool-electrode is transferred to according to the method for the working nitride semiconductor crystal of claim 1.
14. method according to the working nitride semiconductor crystal of claim 13, wherein by using surface roughness Ry less than 10 μ m and glacing flatness described tool-electrode less than 20 μ m, remove the inhomogeneities on the described plane of crystal, to obtain surface roughness Ry less than 10 μ m and glacing flatness smooth surface less than 20 μ m.
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| JP2005184367 | 2005-06-24 | ||
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| CN1883859A true CN1883859A (en) | 2006-12-27 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8592948B2 (en) | 2008-09-08 | 2013-11-26 | Sumitomo Electric Industries, Ltd. | Substrate, epitaxial layer provided substrate, method for producing substrate, and method for producing epitaxial layer provided substrate |
| CN105870006A (en) * | 2016-06-08 | 2016-08-17 | 江苏新广联半导体有限公司 | Processing technology for sidewall of GaN-based material |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8592948B2 (en) | 2008-09-08 | 2013-11-26 | Sumitomo Electric Industries, Ltd. | Substrate, epitaxial layer provided substrate, method for producing substrate, and method for producing epitaxial layer provided substrate |
| CN105870006A (en) * | 2016-06-08 | 2016-08-17 | 江苏新广联半导体有限公司 | Processing technology for sidewall of GaN-based material |
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